1. Field of Application
The invention relates to medical instruments to to be used in the field of ophthalmology, and more specifically, it deals with an ophthalmorheographic transducer for examination of the eye hemodynamics.
2. Description of the Prior Art
Recording variations of the impedance of the eye tissues is an important technique in the examination of blood circulation in the eye. The design of an ophthalmorheographic transducer used for this purpose is vitally important.
Known in the art is a Bettelheim ophthalmorheorgaphic transducer having a casing which is made of an insulating material and has a spheric inner surface for engaging the surface of the eyeball, electrodes on the inner surface of the casing, and a pipe for connecting the casing to a vacuum source (cf. A. P. Nesterov et al. Intraocular Pressure (Physiology and Pathology). Moscow., Nauka Publishing House, 1974, pp. 194-207). When this transducer is used, contact between the eyeball surface and electrodes and retention of the transducer casing on the eye are accomplished by providing vacuum between the inner surface of the casing and the surface of the eyeball. However, because of compression of the eye caused by vacuum application, hemodynamics of the eye is disturbed, and the resultant rheographic recording cannot be considered as reliable. In addition, it is difficult to ensure uniform pressure of the electrodes. Practice has shown that it is only the central portion of the transducer casing that is intimately pressed and retained, the intimacy of contact along the edges being affected so that impedance is mainly a function of the contact surface area rather than a function of changes in blood filling.